The image forcing apparatus of electrophotographic system, for example, a full-color image forming apparatus, provides output typically in a manner such that using toners of three colors, yellow, cyan, and magenta, or toners of four colors with black added to the three colors, dots of each color toner are to rood on an lavage support such as a sheet of papery thereby allowing a full-color image to be visually identified as a whole.
In an electrophotographic system, halftone images can be formed, for example, according to data obtained by performing screen processing using a dither matrix on image data to be turned into a manuscript.
On the other hand, the color toner has been used in combination with a clear toner, thereby allowing the resulting image to have a gloss. To form glossy images, carious types of clear toner images have been suggested.
For example, disclosed in Patent Literatures 1 and 2 is to form a clear toner image so treat a clear toner does not exist on the parallel lines of a color toner image formed through the screen processing but the clear toner exists between the parallel lines.
Furthermore, disclosed in Patent Literatures 3 and 4 is to form a clear toner image using a screen having a greater number of lines than that of a screen used to form a color toner image.
However, there was the problem with the method disclosed in Patent Literatures 1 and 2 that in practice, a positional deviation tends so occur in the position of adhesion, of the clear toner because the resist is controlled with, difficulty, thereby causing the resulting image not to be smoothed and thus not to be glossy as intended. There was also the problem with the method disclosed in Patent Literatures 3 and 4 chat in forming a toner image using a screen having a large number of lines, precise control has to be provided to the diameter of a laser beam used for exposure. However, there is a limit to the preciseness of the control, and the use of the screen may result in degradation in image quality due to interference such as moire.